privatepang Posted 29May Report Share Posted 29May So sent my 74 911 (with 84 Carrera engine) in for a major service and cars been running like crap (lumpy) since I got it back , had the crank angle sensor replaced as it went cactus. Noticed that this vacuum line marked as number 2 on the solenoid seems to not be connected and can't seem to find anywhere obvious that it should be connected to... Anyone have guidance ? Quote Link to comment Share on other sites More sharing options...
Peter M Posted 2June Report Share Posted 2June That looks like a later 964/993 inlet manifold. That's called a change over valve and it is used to operate the resonance flap in the inlet manifold. I presume since it is disconnected that the flap has been removed completely or wired open. The flap is used to improve bottom end torque by changing the resonance response of the manifold. The flap usually opens at about 5,000rpm or so to improve top end torque. If you have a modern ECU they usually have the capacity to operate the flap. Just have to tune the opening on a dyno to maximise the effect. Yeatesy and Russ 2 Quote Link to comment Share on other sites More sharing options...
sus911 Posted 2June Report Share Posted 2June i WAS WONDERING WHY i COULDN'T FIND IT ON MY CAR...... Peter M 1 Quote Link to comment Share on other sites More sharing options...
WOKA Posted 3June Report Share Posted 3June I was going to suggest it connects to the vacuum line connector.. I'll leave quietly. Peter M 1 Quote Link to comment Share on other sites More sharing options...
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